CN100409727C - vacuum plasma generator - Google Patents

Abstract

The invention relates to a vacuum plasma generator (1, 1a, 60) for treating workpieces in a vacuum chamber (17), comprising: a power supply connection (2) for connection to a voltage supply network; at least one power supply a rectifier (3) connected to at least one first converter (4, 4a) for generating at least one intermediate circuit voltage; a first radio frequency signal generator (6, 7, 20, 40, 50) connected to The at least one intermediate circuit voltage for generating a first signal having a fundamental frequency and a first phase position, in particular in the range 1 to 30 MHz; a second radio frequency signal generator (6, 7, 20, 40 , 50), which is connected to the intermediate circuit voltage, for generating a second signal with a fundamental frequency and a second phase position; at least one 3dB coupler (13, 77-91), for the first and second signal is coupled into an output signal and passed directly or indirectly to the generator output (14, 92).

Description

vacuum plasma generator

technical field

The invention relates to a vacuum plasma generator for treating workpieces in a vacuum chamber.

technical background

Vacuum plasma generators of this type can be used, for example, for coating and etching in semiconductor production. The process often requires several kilowatts of radio frequency (RF) power ranging from 1 to 30 MHz. Plasma loading, ie plasma processing in a vacuum chamber, is highly dynamic and prone to arcing, which leads to mismatches and thus reflections in RF applications.

Most vacuum plasma generators include at least one amplifier to generate a high energy radio frequency signal. If there is a mismatch, the energy is reflected by the load. Only a part (usually a very small part) of the reflected energy is absorbed in the amplifier of the vacuum plasma generator and converted into heat. Most of the energy is also usually reflected by the amplifier, which produces multiple reflections and thus standing waves. This generates a lot of energy which oscillates between the amplifier and the plasma load and can cause damage to the plasma load and the amplifier.

US 6,703,080 B2 discloses a generator which can be connected to a switching power supply and connected to a driver stage. This driver stage supplies the RF signal to the amplifier stage, where the RF signal is first distributed over several paths, then amplified on these paths, and finally recoupled into an amplified RF signal in a 3dB coupler. An isolation stage with a circulator is used to cancel the effect of load impedance changes on the amplifier stage.

Vacuum plasma generators should be of minimum size so that they can be mounted close to the vacuum chamber to avoid the need for long and expensive cables.

In semiconductor production, these generators must meet clean room requirements. There should be no forced air exchange using ventilation equipment between the generator interior and the ambient air. These vacuum plasma generators are used in different countries with different supply voltages and frequencies. They are mainly used in industry and therefore must meet the requirements of high immunity to interference, where high interference voltages are mainly present in the supply network and loads.

Contents of the invention

The object of the present invention is to provide a vacuum plasma generator which has low operating losses and is hardly affected by external disturbances and which requires only a minimum number of components, is small in size and offers a variety of uses (in as many countries and fields as possible use).

Above-mentioned object is achieved according to the present invention, and vacuum plasma generator of the present invention comprises:

a power supply connection for connection to a voltage supply network;

at least one power rectifier connected to the

at least one first converter for generating at least one intermediate circuit voltage;

a first radio frequency signal generator connected to the at least one intermediate circuit voltage for generating a first signal having a fundamental frequency and a first phase position, in particular in the range 1 to 30 MHz;

a second radio frequency signal generator connected to the intermediate circuit voltage for generating a second signal having a fundamental frequency and a second phase position;

at least one 3dB coupler for coupling said first and second signals into an output signal and transmitting the output signal indirectly or directly to

generator output.

The advantage of power rectifiers and converters is their insensitivity to interference from the power supply. In particular, with the controllable intermediate circuit voltage temporary mains failures and/or mains voltage drops can be compensated for. This is an important condition especially for generators used in semiconductor production.

When using mains rectifiers, the voltage supply network can be either an AC voltage network with different frequencies or a DC voltage network. Especially in DC voltage networks, the power rectifier should have reverse polarity protection.

The 3dB coupler is a quadruple gate. Ideally, when the signal passes through the 3dB coupler, there will be a 45° phase shift. In fact, there is some degree of skew due to transit time. When two RF signals with a phase shift of 90° enter the gates A and B, one RF signal undergoes a +45° phase shift and the other signal undergoes a -45° phase shift during the process of reaching the gate C, so respectively by the first The signals supplied by the first and second RF signal generators to gates A and B cancel each other at gate C, so that there is no power at gate C. Since the signals of the first and second signal generators are phase-shifted by -45° and +45° respectively in the 3dB coupler and thus are in phase at the gate D, the combination of the two RF signal generators Power appears at gate D. When a load compensation resistor is provided at Gate C, there is no power dissipation at this location and 100% of the power is delivered to the plasma load connected to Gate D.

The 3dB coupler has one decisive advantage over many other couplers. The 3dB coupler divides the reflected power into two paths and sends it back to the RF signal generator. The amplitudes of the two reflected signals are the same, but the signals are phase shifted by 90°. When the RF signal generators to be synthesized have the same structure, their reflection coefficients are also the same. The power reflected by the load is thus reflected by the RF signal generator. Due to the phase rotation during reflection, the reflected power is not sent back to the load, but instead is transferred to the load compensation resistor at gate C. If the latter is terminated by a snubber resistor R=Z ₀ =characteristic wave impedance, the power reflected by the load is completely consumed in this snubber resistor and is no longer reflected. The reflected RF signals cancel each other out at gate D. This is one of the most important advantages of combining two RF signal generators via a 3dB coupler, eliminating multiple reflections.

The 3dB coupler thus forms a protection circuit that prevents damage to the connected RF signal generator in case of reflections due to different load conditions, thus allowing transistorized RF signal generators to be used in this application. can also run safely.

Therefore, changes in the impedance of the load have only a minimal effect on the stability of the generator. The generator is also distinguished by its particularly simple construction. Especially compared with the prior art, it does not need a splitter to split the radio frequency power into at least two paths. The circulator can also be omitted. It is especially advantageous that the second radio frequency signal generator can be connected to the same intermediate circuit voltage.

In a preferred embodiment, the first and second signal generators can each be designed as inverters driven by open-loop and/or closed-loop control means. Especially by appropriately driving the inverter, phase adjustment of the inverter output signal can be facilitated. This makes phase adjustment especially flexible. When the signal paths comprising different inverters have different lengths, the resulting phase differences can be compensated in a simple way. Another advantage of this inverter is that it can be operated as an amplifier. The frequency of the RF signal, especially the RF AC voltage, can be varied by suitable driving. The adjusted phase position can then be substantially maintained. Frequency variation is advantageous when the impedance of the vacuum plasma generator is matched to the plasma impedance without changing the impedance matching network.

RF plasma processing typically utilizes fixed impedance matching networks that cannot be adjusted dynamically, so-called fixed matching devices. In order to match the impedance, the fundamental frequency should vary within predetermined limits. The residual mismatch is acceptable, which produces multiple reflections in conventional vacuum plasma generators. The vacuum plasma generator of the present invention eliminates multiple reflections.

Each inverter preferably includes at least one switching element switched on and off at a fundamental frequency. The switching element may be a transistor, especially a MOS-FET transistor.

For each inverter, the closed-loop and/or open-loop control means preferably have a synchronous drive control output for amplitude modulation, in particular pulse modulation of radio frequency power. In modern vacuum plasma processing, amplitude modulation, especially pulse modulation, is increasingly required. For this case, the generator of the invention has clear advantages. During amplitude modulation, mainly pulse modulation, the load changes, especially dynamically. Impedance matching is not possible with the pulse frequency in most cases. The pulse frequency is usually between 100Hz and 100kHz. Impedance matching is not possible at these frequencies because the impedance matching network reacts too slowly, that is, reflections occur. The generator of the present invention is able to prevent multiple reflections, in particular preventing reflected power from being reflected back into the plasma process.

The advantage of using a 3dB coupler is especially evident when connecting to an inverter. Reflected power can interfere with inverter operation. Reflections, especially multiple reflections, can interfere with the inverter, especially in circuits with a pulse-shaping network at the back end of the inverter to operate the switching elements with minimum losses (when the minimum voltage Acting on the switching element, the element is switched on). Therefore, the 3dB coupler provides more security for the operation of these inverter circuits. By controlling the intermediate circuit voltage, the power of these inverter circuits can be controlled. In this case, low-loss and easy-to-implement inverters can be used, such as those containing only one switching element.

In a preferred further development, each inverter may comprise a half bridge or a full bridge. The power of the bridge circuit can be controlled using pulse width modulation and phase shift modulation. It is then no longer necessary to control the power via an intermediate voltage.

The power at the output of the generator can also be controlled by the phase difference between the two inverters. When the phase changes of the signals from the two inverters are not 90°, only a part of the power is delivered to the generator output and the other part is delivered to the load compensation resistor. This provides fast power control.

In an advantageous embodiment of the present invention, the rear ends of the first and second radio frequency signal generators are both connected to a pulse shaping network. A rectangular or digital signal is provided at the output of each inverter. This signal can be converted to a sinusoidal signal by a pulse shaping network. Harmonics can thus be filtered out and the switching elements of the inverter can be switched with extremely low losses. Advantageously, the pulse shaping network substantially matches the fundamental frequency. Further inverters can be provided with a pulse-shaping network connected at the back end. In addition, further 3dB couplers can also be provided, which couple radio frequency signals in cascaded fashion, in particular to the output connection of the vacuum plasma generator.

Transformers for galvanic decoupling can be omitted when inverters, pulse-shaping networks, or 3dB couplers decouple galvanically through capacitors at their outputs.

In a particularly preferred embodiment, the 3dB coupler comprises at least one first electrical conductor and a second electrical conductor, the first and second electrical conductors are separated and capacitively and inductively coupled to each other, wherein the first The electrical conductor represents the primary side of the transformer, the second electrical conductor represents the secondary side of the transformer, and the number of turns of both the first and second electrical conductors is n>1. The inductance can be simply increased using this simple method. Inductance (coupled inductance) is proportional to the square of the number of turns. Doubling the number of turns quadruples the inductance. So when the number of turns is doubled, the size of the inductance increasing element is reduced by a factor of four. By using more than one turn of the coil, the size can be reduced. If the number of turns is large enough, no further inductance increase is ideally required. The 3dB coupler can thus operate at frequencies below 100MHz, i.e. operating at a frequency higher than that according to US

The prior art of 6,703,080B2 is much lower, i.e. transmission line theory can be disregarded.

In an alternative or other method for increasing the inductance, the 3dB coupler includes at least one inductance increasing element in the coupling region for increasing the inductance of the conductor. Thus the inductance increasing element may have any shape. Preferably, at least a part of the conductor is surrounded in the coupling region. For example, it can be parallel to the conductors to obtain a very simple and efficient coupling. The inductance increasing element preferably surrounds the conductor in a ring shape in the coupling region. A ring shape here means that the conductor part in the coupling region is surrounded by a substantially closed geometric structure, which may be circular, elliptical, rectangular or the like. The ring geometry helps to reduce stray fields. The inductance increasing element can be designed as a ferrite.

The capacitive coupling requiring the use of coupling capacitors can be realized economically and with high reproduction accuracy by means of two electrical conductors with defined surfaces and spaced apart from one another.

By designing the conductor as a flat strip conductor at least in the coupling region, both a compact arrangement and an easy reproducibility can be achieved.

Coupling capacitors and inductors are preferably fabricated using flat strip conductors on the board. The advantage of the plate is that the loss coefficient tanδ is low. To minimize losses in the dielectric material, tan δ should be below 0.005. Initial experiments showed that RT/duorit 5870 from ROGERS was very suitable, with tan δ between 0.0005 and 0.0012 and ε _r of 2.3.

By implementing the strip conductors in a multilayer board, a 3dB coupler can be implemented with minimal expense.

An embodiment of the invention is characterized in that the length of the at least one first and/or second electrical conductor is <λ/4, preferably <λ/8, especially preferably <λ/10. With these values, the transmission line theory of RF technology is no longer important. The 3dB coupler used within the scope of the invention is not a line coupler known in the prior art for higher frequencies, that is to say the 3dB coupler is not characterized (at all) by the line length. Coupling between electrical conductors corresponds to capacitive coupling with a given and adjusted fixed capacitance between conductors having a predetermined fundamental frequency f and a predetermined characteristic wave impedance Z ₀ . Capacitance can be adjusted by the conductor surface and the spacing between conductors. This coupling also corresponds to inductive coupling with a given and adjusted fixed inductance of a transformer with a predetermined fundamental frequency f and a predetermined characteristic wave impedance Z ₀ . For example, the inductance is adjusted as a function of the length of the conductor, especially the length of the conductor segment. In one embodiment of the invention at least one inductance increasing element is provided in the coupling region to increase the inductance of the conductor.

Preferably, the size of the 3dB coupler as a unit is smaller than λ/10. Preferably, this dimension is less than 20 cm x 10 cm x 10 cm for frequencies between 1 and 30 MHz and powers up to 12 kw, which allows integration of the 3dB coupler into existing conventional small housing shapes of vacuum plasma generators.

Preferably, the 3dB coupler is connected to a coolant cooling system. This eliminates the need for interference-sensitive and expensive air cooling systems. Preferably, the entire generator is cooled using coolant, with no forced air exchange, such as by means of ventilation, between the interior of the generator and ambient air. Forced air movement inside the generator is thus possible, where heat is transferred from the air to the cooling liquid by heat exchange.

To realize the expected function of the 3dB coupler, the coupling inductance of the transformer and the coupling capacitance should meet the following conditions:

L _K ＝ Z ₀ /(2πf)

C _K ＝1/(2πfZ ₀ )

in:

L _K = coupled inductance

C _K = coupling capacitance

Z ₀ = characteristic wave impedance

f = frequency

Under the conditions of 13MHz and Z ₀ =50Ω, a coupling inductance L _k of about 600nH and a coupling capacitance C _k of about 200pF can be obtained.

Since 50 ohms is a common value for connecting devices and cables, a vacuum plasma generator is typically provided with an output resistance of 50 ohms. Since the 3dB coupler is used inside the vacuum generator, it can also be realized with a lower characteristic wave impedance. When the characteristic wave impedance of the 3dB coupler is <50 ohms, preferably <20 ohms, its size can be smaller because smaller inductance adding elements are required. When the load impedance is less than 50 ohms, the impedance matching network can be omitted. If impedance matching is required, an impedance matching network is provided to match the impedance of the generator to the plasma load. The impedance matching network can be arranged in the generator, or directly in the vacuum chamber. In the first case, the output signal of the 3dB coupler is passed indirectly, ie via an impedance matching network, to the output of the generator.

Preferably, at least two converters are provided for generating the intermediate circuit voltage, wherein each converter is associated with at least one radio frequency signal generator, which allows independent regulation or control of each intermediate circuit voltage.

The intermediate circuit voltage can be precisely adjusted when the at least one converter comprises an input for connection to an open-loop and/or closed-loop control device and when the converter can be controlled and/or regulated. In particular, the intermediate circuit voltage can be controlled open-loop and/or closed-loop in order to obtain a constant voltage value.

The open-loop and/or closed-loop control device is preferably designed as a programmable logic device, in particular a DSP. The inverter (RF signal, phase difference of the RF signal) and the converter (intermediate circuit voltage) are preferably open-loop and/or closed-loop controlled by structured devices, especially programmable logic devices, preferably a single DSP.

In a preferred embodiment, the converter is designed as a boost converter and/or a buck converter. For this reason, voltages from 200V to 400V can be set at their outputs. The mains voltage varies from country to country. The converter can be connected to supply voltages ranging from 200V to 400V. A constant or closed-loop controlled intermediate circuit voltage of 300V requires both a boost converter and a buck converter.

Power rectifiers, converters, RF signal generators, 3dB couplers, and if required pulse shaping networks and controllers, are preferably integrated in one metal housing. In this way, the vacuum plasma generator is very insensitive to interfering radiation and can also be operated in a very good steady state. The structure can be further compressed.

The vacuum plasma generator preferably includes a power filter so that the vacuum plasma generator is less sensitive to disturbances and harmonics from the network and can operate more stably.

The vacuum plasma generator preferably has a protection circuit against overvoltage from the power supply and also preferably a protection circuit against overvoltage from the generator output, which makes the operation of the vacuum plasma generator more stable.

Description of drawings

Preferred embodiments of the invention shown in the drawings will be explained in more detail hereinafter by referring to the figures of the drawings.

Fig. 1 is the first embodiment of vacuum plasma generator;

Fig. 2 is the second embodiment of vacuum plasma generator;

Figure 3 is an inverter designed as a full bridge with a pulse shaping network;

Figure 4 is an inverter designed as a half bridge with a pulse shaping network;

Figure 5 is an inverter with switching elements;

Figure 6 is an inverter designed as a full bridge and includes decoupling capacitors;

Figure 7 is a part of a vacuum plasma generator with a 3dB coupler network;

Figure 8 is a further illustration of a portion of a vacuum plasma generator with a 3dB coupler network.

Detailed ways

FIG. 1 shows a vacuum plasma generator 1 . The vacuum plasma generator 1 comprises a mains connection 2 which supplies a mains rectifier 3 with a mains voltage. A mains filter and a protection circuit for protection against overvoltage from the mains can be integrated at a location before or after the mains rectifier 3 . The DC voltage generated by the mains rectifier 3 is supplied to a converter 4 which generates an intermediate circuit voltage at a point 5 . The converter 4 can be designed as a DC/DC converter, for example. This intermediate circuit voltage is supplied to the first and the second radio frequency signal generator 6,7 simultaneously. The radio frequency signal generators 6 and 7 are designed as inverters in this embodiment. Radio frequency signal generators 6,7 are connected to pulse shaping networks 10,11 via capacitors 8,9. Open-loop and/or closed-loop control means 12 are used to control the radio frequency signal generators 6 , 7 . The amplitude and phase of the output signals of the radio frequency signal generators 6 , 7 can be adjusted by open-loop and/or closed-loop control means 12 . The frequency of the output signal of the radio frequency signal generator 6 , 7 can also be adjusted via the open-loop and/or closed-loop control device 12 designed as a logic device. In particular the phases of the output signals of the radio frequency signal generators 6, 7 are adjusted so that the signals applied to the 3dB coupler 13 have a phase shift of 90°. This optimizes the power coupling at the output 14 . In the case of optimal phase position and matched load, the load compensation resistor 15 does not dissipate any energy. In order to match the impedance, an impedance matching network 16 may be connected between the 3dB coupler 13 and the vacuum chamber 17 .

A closed-loop and/or open-loop control device 12 is also connected to the control input 18 of the converter 4 so that the intermediate circuit voltage at the point 5 can be adjusted.

The protection circuit used to prevent the overvoltage output by the generator can be arranged directly at the output terminal 14 of the generator, or arranged at the signal Produced on paths 6, 8, 10 or 7, 9, 11.

Compared with FIG. 1, in FIG. 2, functionally identical elements have the same reference numerals as in FIG. circuit voltage. The open-loop and/or closed-loop control device 12 controls the converters 4 and 4a accordingly. Reference numeral 1a in FIG. 2 denotes a vacuum plasma generator, and reference numeral 18a denotes an input terminal of a converter 4a. The open-loop and/or closed-loop control device 12 is represented by a unit. However, it is also possible to split the open-loop and/or closed-loop control unit 12 into a plurality of control components for controlling the converters 4 , 4 a and the radio frequency signal generators 6 , 7 . Several independent open-loop and/or closed-loop control devices can also be provided.

FIG. 3 shows a radio frequency signal generator 20 designed as an inverter and including a full bridge. The full bridge consists of four switching elements 21-24 designed as MOS-FET transistors. The radio frequency signal generator 20 is connected via terminal 25 to a positive intermediate circuit voltage and via terminal 26 to a negative intermediate circuit voltage or a low potential of the intermediate circuit voltage. The switching elements 21-24 have connections 27-30 which provide the control connection of the switching elements 21-24. The full bridge is connected to a pulse shaping network 31 which acts as a bandpass filter and includes a radio frequency signal output 32 . In a particularly preferred embodiment, the pulse shaping network 31 is realized not as a bandpass filter, but as a lowpass filter comprising several LC elements.

Figure 4 shows a radio frequency signal generator 40 designed as an inverter and comprising a half bridge. In this case, the half bridge consists of two switching elements 21 , 22 which are designed as MOS-FET transistors and are connected in series with each other. They also contain connections 27 , 28 serving as control inputs. The radio frequency signal generator 40 can also be connected to the intermediate circuit voltage via the connections 25 , 26 . The radio frequency signal generator 40 provides the radio frequency signal to the radio frequency signal output terminal 32 through the pulse shaping network 31 .

As shown in FIG. 5 , a radio frequency signal generator 50 designed as an inverter can also be connected to the intermediate circuit voltage via terminals 25 , 26 . The RF signal generator 50 has only one switching element 22 designed as a MOS-FET transistor. The radio frequency signal generator 50 provides radio frequency signals to the radio frequency signal output terminal 32 through the pulse shaping network 31 . The radio frequency signal generator 50 is also called a class E amplifier.

FIG. 6 basically reproduces the radio frequency signal generator 20 connected to the pulse shaping network 31 . Capacitors 51, 52 are used for current decoupling. The capacitor 51 is connected between the pulse shaping network 31 and the radio frequency signal output terminal 32 . Capacitor 52 is connected between terminal 26 and ground 53 of the generator. In addition, it has proven to be advantageous to connect an additional capacitance (not shown in FIG. 6 ) between connection 25 and ground 53 . In a particularly preferred embodiment of the circuit shown in FIG. 6, the pulse-shaping network 31 is realized not as a band-pass filter, but as a low-pass filter comprising several LC elements.

FIG. 7 shows a part of the vacuum plasma generator 60 . The vacuum plasma generator 60 includes a core open-loop and/or closed-loop control device 12 . To the open-loop and/or closed-loop control device 12 , 16 modules 61 - 76 are connected. Each of the modules 61-76 contains an RF signal generator and a pulse shaping network. Every two of the modules 61-76 are connected to one of the 3dB couplers 77-84, respectively. In the next stage, two 3dB couplers 77-84 are each connected to a 3dB coupler 85-88. Two 3dB couplers 89, 90 are provided in the third stage and one 3dB coupler 91 is provided in the fourth stage. On the output terminal 92 of the 3dB coupler 91, the radio frequency power to be supplied to the vacuum chamber is applied. This power is detected by the measuring device 93 and transmitted to the closed-loop and/or open-loop control device 12 . The closed-loop and/or open-loop control device 12 is connected to the modules 61-76 via an analog signal data line 94, an interface 95 and an error message line 96 for data exchange. The closed-loop and/or open-loop control means 12 also includes sixteen synchronous clock outputs 97, each of which is provided to a module 61-76. Through these outputs 97, the radio frequency signal generators are clocked at the fundamental frequency. The signals of the clock output 97 are not in phase, which allows the phase of the output signals of the modules 61-76 to be set. The closed-loop and/or open-loop control device 12 also includes sixteen sync pulse outputs 98 . These synchronized pulsed outputs are required if the RF output signal of the vacuum plasma generator 60 is not applied in continuous form but in pulsed form.

FIG. 8 also shows a vacuum plasma generator 60 . Load compensation resistors (not shown) are placed at the output terminals 100-114 of the 3dB couplers 77-91. The voltage across these load compensation resistors is transmitted to the closed-loop and/or open-loop control device 12 via fifteen analog inputs 115 . The voltage detected in this way is a measure of impedance matching, a measure of the phase position of the signals of these RF signal generators relative to each other, and a measure of the power symmetry of the signals of these RF signal generators relative to each other. These voltages can also be used for closed loop control of the vacuum plasma generator 60 .

Claims (19)

1. a vacuum plasma generator (1,1a, 60) is used for handling the workpiece of vacuum chamber (17), comprising:

Power connector end (2) is used to be connected to the voltage supply network;

At least one power rectifier (3), it is connected to

(4,4a), this first transducer is used to produce at least one intermediate circuit voltage at least one first transducer;

First radio-frequency signal generator (6,7,20,40,50), it is connected to described at least one intermediate circuit voltage, is used to produce first signal with fundamental frequency and first phase position;

Second radio-frequency signal generator (6,7,20,40,50), it is connected to intermediate circuit voltage, is used to produce the secondary signal with described fundamental frequency and second phase position;

At least one three-dB coupler (13,77-91), be used for described first and second signals are coupled into output signal, and this output signal is sent to generator output end (14,92) indirectly or directly.

2. generator as claimed in claim 1 is characterized in that, the fundamental frequency of this first signal that this first radio-frequency signal generator produces is in 1 to 30MHz scope.

3. generator as claimed in claim 1 is characterized in that, each all is designed to the inverter that driven by open loop and/or closed-loop control device (12) described first and second radio-frequency signal generators (6,7,20,40,50).

4. generator as claimed in claim 3 is characterized in that each inverter has half-bridge or full-bridge.

5. each described generator in the claim as described above is characterized in that providing at least one electric capacity (8,9,51,52), is used for the electric current decoupling.

6. as each described generator in the claim 1 to 3, it is characterized in that pulse forming network (10,11,31) is connected in described first and second radio-frequency signal generators (6,7,20,40,50) after each.

7. generator as claimed in claim 1, it is characterized in that, described three-dB coupler (13,77-91) comprise at least one first electric conductor and second electric conductor, described first and second electric conductors are spaced, and capacitively with inductive intercouple, wherein said first electric conductor is represented the primary side of transformer, described second electric conductor is represented the primary side of transformer, and the number of turn of described first and second electric conductors is n＞1.

8. generator as claimed in claim 1, it is characterized in that, described three-dB coupler (13,77-91) comprise at least one first electric conductor and second electric conductor, described first and second electric conductors are spaced, and capacitively with inductive intercouple, wherein said first electric conductor is represented the primary side of transformer, described second electric conductor is represented the primary side of transformer, and wherein provides at least one inductance to increase element in coupling regime, increases the inductance of described electric conductor.

9. as claim 7 or 8 described generators, it is characterized in that the length of described at least one first electric conductor and/or second electric conductor is less than λ/4.

10. generator as claimed in claim 9 is characterized in that, the length of described at least one first electric conductor and/or second electric conductor is less than λ/8.

11. generator as claimed in claim 9 is characterized in that, the length of described at least one first electric conductor and/or second electric conductor is less than λ/10.

12., it is characterized in that (13, the characteristic wave impedance that 77-91) has is less than 50 ohm for described three-dB coupler as each described generator in the claim 1 to 3.

13. generator as claimed in claim 12 is characterized in that, (13, the characteristic wave impedance that 77-91) has is less than 20 ohm for described three-dB coupler.

14. as each described generator in the claim 1 to 3, it is characterized in that, provide at least two transducers (4,4a), be used to produce intermediate circuit voltage, wherein each transducer (4,4a) with at least one radio-frequency signal generator (6,7,20,40,50) be associated.

15. as each described generator in the claim 1 to 3, it is characterized in that, described at least one transducer (4,4a) comprise an input (18,18a), be used to connect open loop and/or closed-loop control device (12).

16. generator as claimed in claim 15 is characterized in that, described open loop and/or closed-loop control device (12) are designed to programmable logic device.

17. generator as claimed in claim 16 is characterized in that, described programmable logic device is a digital signal processor.

18., it is characterized in that for described vacuum plasma generator (1,1a, 60) provides an impedance matching circuit (16), the impedance that is used to regulate described generator (1,1a, 60) is with the match plasma load as the described generator of claim 1 to 3.

19. as each described generator in the claim 1 to 3, it is characterized in that, and described transducer (4,4a) be designed to boost converter and/or step-down controller.

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